1. Field of the Invention
The present invention relates to a cathode for a lithium-air battery and a lithium-air battery comprising the same, and more particularly, to a cathode for a lithium-air battery, which may lower the charge voltage of a lithium-air battery, thus enabling the lithium-air battery to have improved energy efficiency and superior cycle life of charge and discharge, and to a method of manufacturing the same and a lithium-air battery comprising the same.
2. Description of the Related Art
A lithium-air battery indicates a battery that uses lithium (Li) metal as an anode and oxygen (O2) in air as a cathode active material, and is a novel energy storage system able to substitute for a conventional lithium ion battery. This lithium-air battery is a battery system wherein oxidation/reduction of lithium at an anode and reduction/oxidation of oxygen supplied from the outside at a cathode occur and also wherein secondary battery and fuel cell technologies are combined. The theoretical energy density of the lithium-air battery is 11,140 Wh/kg, which is much higher than those of other secondary batteries.
The lithium-air battery typically includes an anode, a cathode, and an electrolyte and a separator between the anode and the cathode. The cathode is typically composed of porous carbon and a binder. However, the carbon material reacts with lithium peroxide (Li2O2) produced during discharge of the lithium-air battery, and promotes the decomposition of an organic electrolyte, thus forming byproducts such as lithium carbonate (Li2CO3), etc. Also, the binder used to manufacture the cathode is known to decompose due to the reaction with lithium peroxide. Thereby, the lithium-air battery is disadvantageous because its charge voltage is very high and charge and discharge energy efficiencies are remarkably low, and the life of the battery is very short due to byproducts which continuously accumulate during the cycle. Therefore, the development of a cathode able to decrease the charge voltage of a lithium-air battery and to increase the cycle life, without including carbon and a binder, is required.